Following up on this for the morbidly curious....
As seen previously in this thread, I finished putting the bike together with the 49-42-32 crank and the 13-24 casseete last week. On Saturday, I took it out for a test ride. Ironically, the route I was riding was extremely flat. It did have a couple of rolling hills though. RideWithGPS claims one pitch got as steep as 5%. Very short, maybe 100 feet of elevation gain, but enough to feel what the gearing is like. Conclusion: I love it! Really comfortable gearing. Shifting was great. All good.
But I do have a minor glitch in my build to report. Before I took it out, I noticed there was a spot where I felt a bit of drag when rotating the pedals. Not much, just a a little more drag than the rest of the rotation. I had the chain on the middle ring, so it definitely wasn't a chain length issue, so I ignored it. During the ride, I didn't notice at all. Everything felt extremely smooth and efficient. But when I got home I put the bike in the stand to wipe it down, and I felt it again. This time I looked closer to see what was going on. It turned out the inner chainring was very slightly rubbing the chainstay in one spot. Through the rest of the rotation, the small ring was clearing the chainstay by just a hair's width. Oops.
First, let me say I'm very happy to report that even after a 33 mile ride on this, it didn't even scrape this paint down to the primer. That's nothing short of a Festivus miracle, IMO.
I didn't even think this through. I've got another bike with a triplized Campy Strada crankset, so I just used the same bottom bracket length on this one that I had on the first -- UN55 70x122.5. That's the longest Italian threaded square taper I could find, and I didn't even question it. Those of you with deep knowledge of Campy bottom bracket spindle lengths can probably guess what happened here. The crank I triplized before was pre-CPSC, but the one on the Gios was post-CPSC. The post-CPSC crank is designed for a longer spindle -- 115.5 mm asymmetric spindle, offset ~3 mm to the drive side, so I figure equivalent to a 118.5 symmetric spindle; Going to a triple, I want to push the chainline out about 4mm, doubled for the symmetric bottom bracket, so I need about a 126.5 bottom bracket??? I am using a Campy crank on an ISO spindle, so theoretically I should get an extra few mm from that, but I have no idea how many time this crank has been on an off a spindle. tl;dr -- I'm not surprised I had problems.
Solution? There's a guy on eBay (mtbtools) who sells spacers for Italian bottom brackets for a couple of bucks. I knew this because when I built my De Rosa, I discovered that someone had shaved the bottom bracket down to 68mm, so I had to buy a spacer then. I bought another 2mm spacer, put it behind the bottom bracket on the drive side, and Bob's my uncle. I now have daylight between the chainring and the chainstay all the way around.
As Sallah said to Indiana Jones, "I told you it would be alright!"